Along with sophistication of features of electronic device, the wiring in a wiring board is getting more complex and the number of wiring is increasing. On the other hand, the compactness of the electronic device is demanded from the viewpoint of convenience. In efforts to satisfy such inconsistent requests, a means for transmitting signals in the form of serial data so as to reduce the number of wiring has been adopted in the past. A protocol or method “serial peripheral interface (SPI)” stipulating channels in control device, or more particularly, communications among a micro-processing unit and peripheral input/output (I/O) devices has prevailed in the past. Document 1 “Data Sheet TLE4230 GP (Infineon Technologies AG, Bereichs Kommunikation, Aug. 28, 2000)” describes an example of a peripheral input/output device (output driver) using an SPI. A power element described in Document 1 or the like can control the output thereof via either an SPI or an individual signal line. According to the method, an output whose on-off cycle is long such as an output of a relay is controlled through serial communication represented by the SPI method. Consequently, the number of signal lines to be used for control can be largely reduced. Moreover, an output that repeats on-off at intervals of a short cycle such as an output of a pulse-width modulator (PWM) is controlled as an individual signal. Consequently, fast on-off can be achieved during serial communication without the necessity of overhead. Moreover, related arts relating to transfer of serial data synchronous with a clock include the one described in conjunction with FIG. 15 in Document 2 (Japanese Unexamined Patent Publication No. 61-166244).
Non-patent Document 1: Data Sheet TLE4230 GP, Infineon Technologies AG, Bereichs Kommunikation (Aug. 28, 2000)
Patent Document 1: Japanese Unexamined Patent Publication No. 61-166244